In another of his superbly reported insider accounts, "Obama's Wars," Bob Woodward recounts how a new president may well have embroiled himself in a war that could poison his presidency -- just as his predecessor, George W. Bush, destroyed his with a foolhardy war in Iraq and Lyndon Johnson and Richard Nixon were ruined by the war in Vietnam.

The grim mountains and deserts of Afghanistan are a boneyard of invading foreign armies. The British rulers of colonial India sent an Anglo-Indian army into Afghanistan in 1839 to establish it as a buffer state against the advances of imperial Russia in Central Asia. The enterprise faltered against Afghan resistance, and the main garrison at Kabul -- about 4,500 troops and 12,000 family members and camp followers -- decided to retreat back to India in January 1842. Afghan tribesmen fell upon them in the snows of the mountain passes and slaughtered them without pity. Only one man, a doctor named William Brydon, reached safety. A few others were spared as prisoners and subsequently rescued.

One hundred and thirty-seven years later came the turn of the mighty Soviet Union. In December 1979, Leonid Brezhnev dispatched the lead elements of a 110,000-man Soviet expeditionary force to rescue Afghanistan's collapsing communist regime. The Red Army was a proud army. It had smashed Adolf Hitler's Wehrmacht, once thought invincible. But after 10 years of fruitless Afghan warfare, the last elements of a broken and dispirited Soviet force climbed into their armored vehicles and headed north, back into Russia.

The American war in Afghanistan began, of course, in 2001, after the Sept. 11 attacks on the World Trade Center and the Pentagon, and the refusal of the Taliban leadership to hand over Osama bin Laden and the other al-Qaeda leaders who instigated and planned them. Bush, however, neglected Afghanistan in favor of his war in Iraq.

According to Woodward's narrative, Obama seems to have first stepped into the Afghan war in a somewhat absent-minded way, granting the military another 21,000 troops for the conflict, without much examination, during the opening months of his administration.

By the fall, the commanders are back for more. Lt. Gen. Stanley McChrystal, an aggressive and highly regarded officer (until he blew himself up with disparaging comments about his colleagues and superiors in a Rolling Stone interview), had been appointed the new commander for Afghanistan on May 11, 2009. He had toured the country to reassess the situation and had handed in his report at the end of August.

Soon the bad news arrives from the Pentagon. McChrystal wants an additional 40,000 troops, enough reinforcements to virtually equal the size of the Soviet commitment -- 108,000 U.S. forces in Afghanistan when added to the 68,000 already authorized for deployment there. The request is backed by Robert Gates, the secretary of defense; Adm. Mike Mullen, the chairman of the Joint Chiefs of Staff; and Gen. David Petraeus, the most prestigious officer in the Army, thanks to his application of counterinsurgency tactics in Iraq, and the chief of U.S. Central Command, which covers American forces in the Middle East and South Asia from its headquarters in Tampa. (Petraeus took over as commanding general in Afghanistan after McChrystal was sacked for his indiscretion in June 2010.)

As there is minimal mention of Iraq in the book, Woodward takes his title from the resulting arguments that drag on month after month through the fall of 2009 in the Situation Room in the basement of the West Wing.

The military wants the 40,000 troops with no strings attached, no promise that this will be the last request and no fixing of a date when Obama can begin withdrawing them. The president sees the pit opening before him. "This is not what I'm looking for," he says. "I'm not doing 10 years, I'm not doing a long-term nation-building effort. I'm not spending a trillion dollars." He wants another, more flexible option with fewer troops and a built-in date to start withdrawals. But the military won't give it to him. Gates, Mullen and Petraeus hold fast to the original request and put additional pressure on Obama through their supporters in Congress and the media. (The 29,000 NATO forces in Afghanistan do not figure in the argument because many are noncombat support troops and because it is uncertain how much longer allied countries will maintain their contributions.)